1. Field of the Invention
The invention relates to a battery structured such that positive and negative active material layers face each other with an electrolyte layer therebetween and a manufacturing method for such a battery.
2. Description of the Related Art
Conventionally, as a method for producing a chemical battery such as a lithium-ion battery, a technology for superimposing metal foils as current collectors respectively having positive-electrode and negative-electrode active materials attached thereto with a separator disposed therebetween and impregnating the separator with an electrolyte solution has been known. However, a battery including a volatile organic solvent as an electrolytic solution needs to be carefully handled. Further, for required further miniaturization and higher output, a technology for producing an all-solid-state battery by microfabrication using a solid electrolyte in place of an electrolytic solution has been and is being proposed in recent years.
For example, JP2005-116248A discloses a technology for forming an active material layer having an uneven surface on a metal foil, which will become a current collector, by an ink jet method and successively three-dimensionally laminating a solid electrolyte layer and another active material layer by the ink jet method so as to flatten the unevenness.
In the above prior art, the above space structure is obtained by laminating a multitude of layers mixedly including different functional layers such as the positive and negative active material layers and the solid electrolyte layer formed by one printing process by recoating. However, this technology has the following problems.
Firstly, the ink-jet method can form a complicated structure as above with high controllability since only a small amount of ink is discharged, whereas it requires a long time for production since recoating needs to be performed a plurality of times to obtain a desired space structure and is low in productivity. Secondly, it is difficult to separate the respective functional layers. In other words, the functional layers are mixed due to the contact of the ink containing mutually different materials to make boundaries between the respective functional layers unclear, leading to a possibility of reducing performance of the battery. Although drying is performed after every printing process in the above prior art, this further reduces productivity and increases production cost. Even if the mixing of the respective layers formed by the respective printing processes should be prevented, the mixing of a plurality of functional layers formed adjacent to each other by one printing process cannot be prevented.